In video surveillance systems currently available, it is common to have multiple adjustable video cameras located throughout a premises. A security operator, located at a master control panel, has the capability of individually adjusting the viewing or optical axis of each camera by changing the pan and tilt angles of the camera. The operator also has the capability of adjusting the zoom and the focus states of each camera. In this manner, the security operator can sequentially train the optical axes and, therefore, the fields of view of selected cameras on a desired location or object within the premises, thereby advantageously affording multiple viewing angles thereof.
The advantages of multiple viewing angles are readily appreciated in situations where a subject is moving about a premises. As the subject moves, physical parts of the premises, such as doors, walls and furniture, temporarily prevent various cameras from viewing the subject. Also, the subject may be facing away from a single camera thereby shielding the subject's activity or preventing viewing of the subject's face. By simultaneously tracking the subject with more than one camera, multiple viewing angles of the subject are provided and the aforementioned problems are minimized.
In present video surveillance systems, it is very difficult for a security operator to simultaneously control two cameras while tracking a subject moving through a premises. For example, the operator, while viewing the video signal of a first camera, must adjust the optical axis of the first camera, by means of a joystick (or other control device) which controls the panning and tilting of the camera, until the desired subject is viewed. At the same time, or closely thereafter, the operator, while viewing the video output of a second camera, must manipulate a second joystick so as to pan and tilt the second camera to adjust the optical axis of the second camera until the subject is also viewed by the second camera. The operator, thus, often finds himself or herself trying to control the first camera with one hand, and the second camera with the other hand, while watching the video signals of both the first and second cameras, to try to keep both cameras trained on the subject.
As can be appreciated, the difficulty of tracking a subject in this way distracts the operator from the primary task of observing and detecting anomalous situations or actions by the subject. Further, as the number of cameras being used to simultaneously track a subject increases above two, it becomes increasingly difficult, if not impossible, for an operator to effectively track the subject.
Still further, as a subject moves beyond the range of a camera, the operator must determine and manually select the address of a different camera to be included in the tracking. Upon selecting the new address, which in and of itself is a distraction to the operator, the optical axis of the newly selected camera is initially in an unknown state. Therefore, the operator must spend an inordinate amount of time initially panning and tilting the newly selected camera to adjust its optical axis such that it is trained on the subject.
It is, therefore, an object of the present invention to provide a camera surveillance system and method which do not have the aforementioned disadvantages of the known surveillance systems.
It is also an object of the present invention to provide a camera surveillance system and method with multiple surveillance devices and in which improved simultaneous control of the multiple surveillance devices is also provided.
It is a further object of the present invention to provide a camera surveillance system and method with which an operator can easily track, with multiple surveillance cameras, a subject moving through a premises.